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    <h1>
      ENZO parameter list</h1>

    <p>
      The following is a largely complete list of the parameters that
      enzo understands, and a brief description of what they
      mean.  They are grouped roughly by meaning; an <A
      HREF="parameters-sorted.html">alphabetical list</A> is also
      available.  Parameters for individual test problems are also
      listed here.
    </p>

    <p>
      This parameter list has two purposes.  The first is to
      describe and explain the parameters that can be put into the
      initial parameter file that begins a run.  The second is to
      provide a comprehensive list of all parameters that the code
      uses, including those that go into an output file (which
      contains a complete list of all parameters), so that users can
      better understand these output files.
    </p>

    <p>The parameters fall into a number of categories:</p>
    <ul>
      <li>
	  <b class="external">external</b> - These are user parameters
	  in the sense that they can be set in the parameter file, and
	  provide the primary means of communication between the enzo
	  and the user.
      </li>

      <li>
	  <b class="internal">internal</b> - These are mostly not set
	  in the parameter file (although strictly speaking they can
	  be) and are generally used for program to communicate with
	  itself (via the restart of output files).
      </li>
      <li><b class="obsolete">obsolete</b></li>
      <li><b class="reserved">reserved</b></li>
    </ul>

    <p>
      Generally the external parameters are the only ones that are
      modified or set, but the internal parameters can provide useful
      information and can sometimes be modified so I list them here as
      well. Some parameters are true/false or on/off boolean
      flags. Eventually, these may be parsed, but in the
      meantime, I use the common convention of 0 meaning false or off
      and 1 for true or on.
    </p>

    <p>
      This list includes parameters for current version as of June 2003 
      (the cvs revision number v0_2_0).
    </p>

    <h3>Contents</h3>

    <ol>
      <li>
	<a href="#Stopping Parameters">Stopping Parameters</a></li>

      <li>
	<a href="#Initialization Parameters">Initialization Parameters</a></li>

      <li>
	<a href="#I/O Parameters">I/O Parameters</a></li>

      <li>
	<a href="#Hierarchy Control Parameters">Hierarchy Control Parameters</a></li>

      <li>
	<a href="#Hydrodynamic Parameters">Hydrodynamic Parameters</a></li>

      <li>
	<a href="#Cosmology Parameters">Cosmology Parameters</a></li>

      <li>
	<a href="#Gravity Parameters">Gravity Parameters</a></li>

      <li>
	<a href="#Particle Parameters">Particle Parameters</a></li>

      <li>
	<a href="#Parameters for Additional Physics">Parameters for Additional
	  Physics</a></li>

      <li>
	<a href="#Test Problem Parameters">Test Problem Parameters</a></li>

      <li>
	<a href="#Other external Parameters">Other external Parameters</a></li>

      <li>
	<a href="#Other Internal Parameters">Other internal Parameters</a></li>

      <li>
	<a href="#Parameters to be Described">Parameters to be Described</a></li>
    </ol>


    <hr WIDTH="100%">
    <h3>
      <a NAME="Stopping Parameters"></a>Stopping Parameters</h3>

    <ul>
      <li><p>
	  <b class="external">StopTime</b> (external) - This parameter specifies the time (in code
	  units) when the calculation will halt.  For cosmology simulations,
	  this variable is automatically set by CosmologyFinalRedshift.  No
	  default.</p></li>

      <li><p>
	  <b class="external">StopCycle </b>(external) - The cycle (top grid timestep) at which the
	  calculation stops.  A value of zero indicates that this criterion
	  is not be used.  Default: 0</p></li>

      <li><p>
	  <b class="external">StopFirstTimeAtLevel </b>(external) - Causes the 
	  simulation to immediately stop when a specified level is 
	  reached.  Default value 0 (off), possible values are levels 1 through 
	  maximum number of levels in a given simulation.</p></li>

      <li><p>
	  <b class="reserved">StopCPUTime</b> - Reserved for future use.</p></li>
    </ul>

    <h3>
      <a NAME="Initialization Parameters"></a>Initialization Parameters</h3>

    <ul>
      <li><p><a NAME="Problem Type"></a>
	  <b class="external">ProblemType</b> (external) - This integer specifies the type of problem
	  to be run.  It's value causes the correct problem initializer to be
	  called to set up the grid, and also may trigger certain boundary conditions
	  or other problem-dependent routines to be called.  The possible values
	  are listed below.  [Not all of these problems run with more than one processor. 
	  The list of those known to work in parallel are: 23, 25, 30.] 
	  Default: none. For other problem-specific parameters follow the links below.</p>

      <center><table>
	  <tr>
	    <td>1 - <a href="#Shock Tube">Shock Tube</a></td>
	    <td>20 - <a href="#Zeldovich Pancake">Zeldovich Pancake</a></td>
	    <td>25 - <a href="#Test Gravity Sphere">Test Gravity: Sphere</a></td>
	  </tr>
	  <tr>
	    <td>2 - <a href="#Wave Pool">Wave Pool</a></td>
	    <td>21 - <a href="#Pressureless Collapse">Pressureless Collapse</a></td>
	    <td>26 - <a href="#Gravity Equilibrium Test">Gravity Equilibrium Test</a></td>
	  </tr>
	  <tr>
	    <td>3 - <a href="#Shock Pool">Shock Pool</a></td>
	    <td>22 - <a href="#Adiabatic Expansion">Adiabatic Expansion</a></td>
	    <td>27 - <a href="#Collapse test">Collapse Test</a></td>
	  </tr>
	  <tr>
	    <td>4 - <a href="#Double Mach Reflection">Double Mach Reflection</a></td>
	    <td>23 - <a href="#Test Gravity">Test Gravity</td>
	    <td>30 - <a href="#Cosmology Parameters">Cosmology Simulation</a></td>
	  </tr>
	  <tr>
	    <td>5 - <a href="#Shock In A Box">Shock In A Box</a></td>
	    <td>24 - <a href="#Spherical Infall">Spherical Infall</a></td>
	    <td>40 - <a href="#Supernova Restart Simulation">Supernova Restart</a></td>
	  </tr>
	</table></center></li>
	<p></p>

      <li><p>
	  <b class="external">TopGridRank</b> (external) - This specified the dimensionality of the
	  root grid and by extension the entire hierarchy.  It should be 1,2 or
	  3.  Default: none</p></li>

      <li><p>
	  <b class="external">TopGridDimensions</b> (external) - This is the dimension of the top
	  or root grid.  It should consist of 1, 2 or 3 integers separated by
	  spaces.  For those familiar with the KRONOS or ZEUS method of specifying
	  dimensions, these values do not include ghost or boundary zones. 
	  A dimension cannot be less than 3 zones wide and more than MAX_ANY_SINGLE_DIRECTION - 
	  NumberOfGhostZones*2. MAX_ANY_SINGLE_DIRECTION is defined in <b>fortran.def</b>.  
	  Default: none</p></li>

      <li><p>
	  <b class="external">DomainLeftEdge, DomainRightEdge</b> (external) - These float values
	  specify the two corners of the problem domain (in code units).  The
	  defaults are: 0 0 0 for the left edge and 1 1 1 for the right edge.</p></li>

      <li><p>
	  <b class="external">LeftFaceBoundaryCondition, RightFaceBoundaryCondition</b> (external)
	  - These two parameters each consist of vectors of integers (of length TopGridRank). 
	  They specify the boundary conditions for the top grid (and hence the entire
	  hierarchy).  The first integer corresponds to the x-direction, the
	  second to the y-direction and the third, the z-direction.  The possible
	  values are: 0 - reflecting, 1 - outflow, 2 - inflow, 3 - periodic. 
	  For inflow, the inflow values can be set through the next parameter, or
	  more commonly are controlled by problem-specific code triggered by the
	  ProblemType.  Default: 0 0 0</p></li>

      <li><p>
	  <b class="external">BoundaryConditionName</b> (external) - While the above parameters provide
	  an easy way to set an entire side of grid to a given boundary value, the
	  possibility exists to set the boundary conditions on an individual cell
	  basis.  This is most often done with problem specific code, but it
	  can also be set by specifying a file which contains the information in
	  the appropriate format.  This is too involved to go into here. 
	  Default: none</p></li>

      <li><p>
	  <b class="internal">InitialTime</b> (internal) - The time, in "code" units, of the current
	  step.  For cosmology the units are in free-fall times at the initial
	  epoch (see <a href="output.html">output</a> format).   
	  Default: generally 0, depends on problem</p></li>

      <li><p>
	  <b class="internal">Initialdt</b> (internal) - The timestep, in "code" units, 
	  for the current step. For cosmology the units are in free-fall times at the initial
	  epoch (see <a href="output.html">output</a> format).   
	  Default: generally 0, depends on problem</p></li>

      <li><p>
	  <b class="obsolete">GridVelocity</b> (obsolete) - For problems in which the grid must move. 
	  Originally implemented, but was never used, and so almost surely doesn't
	  work.  Default: 0 0 0</p></li>
    </ul>

    <h3>
      <a NAME="I/O Parameters"></a>I/O Parameters</h3>
    There are three ways to specify the frequency of outputs: time-based, cycle-based
    (a cycle is a top-grid timestep), and, for cosmology simulations, redshift-based. 
    There is also a shortened output format intended for visualization (<a href="output.html#movie dumps">movie
      format</a>).
    <ul>
      <li><p>
	  <b class="external">dtDataDump </b>(external) - The time interval, in code units, between
	  time-based outputs.  A value of 0 turns off the time-based outputs. 
	  Default: 0</p></li>

      <li><p>
	  <b class="external">CycleSkipDataDump</b> (external) - The number of cycles (top grid timesteps)
	  between cycle-based outputs.  Zero turns off the cycle-based outputs. 
	  Default: 0</p></li>

      <li><p>
	  <b class="external">DataDumpName </b>(external) - The base file name used for both time
	  and cycle based outputs.  Default: <i>data</i></p></li>

      <li><p>
	  <b class="external">RedshiftDumpName</b> (external) - The base file name used for redshift-based
	  outputs (this can be overridden by the CosmologyOutputRedshiftName parameter).
	  Normally a four digit identification number is appended to the end of this
	  name, starting from 0000 and incrementing by one for every output. This
	  can be over-ridden by including four consecutive R's in the name (e.g.
	  RedshiftRRRR) in which case the an identification number will not be appended
	  but the four R's will be converted to a redshift with an implied decimal
	  point in the middle (i.e. z=1.24 becomes 0124).  Default: <i>RedshiftOutput</i></p></li>

      <li><p>
	  <b class="external">CosmologyOutputRedshift[####]</b> (external) - The time and cycle-based
	  outputs occur regularly at constant intervals, but the redshift outputs
	  are specified individually.  This is done by the use of this statement,
	  which sets the output redshift for a specific identification number (this
	  integer is between 0000 and 9999 and is used in forming the name). 
	  So the statement CosmologyOutputRedshift[1] = 4.0 will cause an output
	  to be written out at z=4 with the name RedshiftOutput0001 (unless the base
	  name is changed either with the previous parameter or the next one). 
	  This parameter can be repeated with different values for the number (####). 
	  Default: none</p></li>

      <li><p>
	  <b class="external">CosmologyOutputRedshiftName[####]</b> (external) - This 
	  parameter overrides
	  the parameter RedshiftOutputName for this (only only this) redshift output. 
	  Can be used repeatedly in the same manner as the previous parameter. 
	  Default: none</p></li>

      <li><p>
	  <b class="external">dtMovieDump </b>(external) - The time interval, in code units,
	  between movie dumps.  A value of 0 turns off the movie dumps. 
	  Default: 0</p></li>

      <li><p>
	  <b class="external">MovieRegionLeftEdge, MovieRegionRightEdge</b> (external) - These two
	  parameters control the region for which movie dumps are made.  When
	  a movie dump is generated (see the section on output format), only those
	  grid points and particles within this region are written out to the movie
	  data files.</p></li>

      <li><p>
	  <b class="external">MovieDumpName</b> (external) - This character parameter is the base
	  name of the movie dumps.  Default: MovieData</p></li>

      <li><p>
	  <b class="external">OutputFirstTimeAtLevel </b>(external) - This forces enzo 
	  to output when a given level is reached, and at every 
	  level thereafter.  Default is 0 (off). User can usefully specify 
	  anything up to the maximum number of levels in a given simulation.</p></li>

      <li><p>
	  <b class="external">XrayLowerCutoffkeV, XrayUpperCutoffkeV, 
	  XrayTableFileName,  </b>(external) - These parameters are used in 2D projections
	  (enzo -p ...). The first two specify the X-ray band (observed at z=0) to be used, 
	  and the last gives the name of an ascii file that contains the X-ray 
	  spectral information.  A gzipped version of this file good for bands 
	  within the 0.1 - 20 keV range is available <a href="lookup_metal0.3.data.gz">
	  here</a>.
	  If these parameters are specified, then the second field is replaced with 
	  integrated emissivity along the line of sight in units of 10^-23 erg/cm^2/s.
	  </p></li>


      <li><p>
         <b class="external">ExtractFieldsOnly </b>(external) - Used for extractions 
	 (enzo -x ...) when only field data are needed instead of field + particle data.  
	 Default is 1 (TRUE).
	 </p></li>

      <li><p>
	  <b class="reserved">dtRestartDump</b> - Reserved for future use.</p></li>

      <li><p>
	  <b class="reserved">dtHistoryDump</b> - Reserved for future use.</p></li>

      <li><p>
	  <b class="reserved">CycleSkipRestartDump</b> - Reserved for future use.</p></li>

      <li><p>
	  <b class="reserved">CycleSkipHistoryDump</b> - Reserved for future use.</p></li>

      <li><p>
	  <b class="reserved">RestartDumpName </b> - Reserved for future use.</p></li>

      <li><p>
	  <b class="reserved">HistoryDumpName</b> - Reserved for future use.</p></li>

      <li><p>
	  <b class="external">ParallelRootGridIO</b> (external) - Normally, for the mpi 
	  version, the
	  root grid is read into the root processor and then partitioned to separate
	  processors.  However, for very large root grids (e.g. 512^3), the
	  root processor may not have enough memory.  If this toggle switch
	  is set on (i.e. to the value 1), then each processor reads its own section
	  of the root grid.  More I/O is required (to split up the grids and
	  particles), but it is more balanced in terms of memory. ParallelRootGridIO and 
	  ParallelParticleIO MUST be set to 1 (TRUE) for runs involving > 64 cpus!
	  Default: 0 (FALSE). See also Unigrid below.</p></li>

      <li><p>
	  <b class="reserved">Unigrid </b>(external) - This parameter must be set to 
	  1 (TRUE) in order to enable some modifications which prevent process 0 from 
	  instantiating a (useless) copy of a top grid sized field. Must be set TRUE for
	  unigrid runs with ParallelRootGridIO = 1 so that large simulations would start
	  on distributed-memory systems. Default: 0 (FALSE)
	  </p></li>

    </ul>

    <h3>
      <a NAME="Hierarchy Control Parameters"></a>Hierarchy Control Parameters</h3>

    <ul>
      <li><p>
	  <b class="external">StaticHierarchy </b>(external) - A flag which indicates 
	  if the hierarchy is static (1) or dynamic (0).  In other words, a value of 1 
	  takes the a out of amr.  Default: 1</p></li>

      <li><p>
	  <b class="external">RefineBy</b> (external) - This is the refinement factor 
	  between a grid and it's subgrid.  For cosmology simulations, I have found 
	  the number 2 to be most useful.  Default: 4</p></li>

      <li><p>
	  <b class="external">MaximumRefinementLevel</b> (external) - This is the lowest 
	  (most refined) depth that the code will produce.  It is zero based, so the total
	  number of levels (including the root grid) is one more than this value. 
	  Default: 2</p></li>

      <li><p>
	  <b class="external">CellFlaggingMethod </b>(external) - The method(s) used to 
	  specify when
	  a cell should be refined. This is a list of integers, up to five, as described
	  by the following table. The methods combine in an "OR" fashion: if any
	  of them indicate that a cell should be refined, then it is flagged.  For cosmology
	  simulations, methods 2 and 4 are probably most useful.  Note that
	  some methods have additional parameters which are described below. 
	  Default: 1</p>

	<center><table>
	      <tr>
		<td>1 - refine by slope</td>
		<td>5 - refine by baryon overdensity (currently disabled)</td>
	      </tr>

	      <tr>
		<td>2 - refine by baryon mass</td>
		<td>6 - refine by Jeans length </td>
	      </tr>

	      <tr>
		<td>3 - refine by shocks</td>
		<td>7 - refine if cooling time &lt; cell width/sound speed</td>
	      </tr>

	      <tr>
		<td>4 - refine by particle mass</td>
                <td> </td>
	      </tr>
	</table></center></li>
	<p></p>

      <li><p>
	  <b class="external">RefineRegionLeftEdge, RefineRegionRightEdge</b> (external) - 
	  These two
	  parameters control the region in which refinement is permitted.  Each
	  is a vector of floats (of length given by the problem rank) and they specify
	  the two corners of a volume.  Default: set equal to DomainLeftEdge
	  and DomainRightEdge.</p></li>

      <li><p>
	  <b class="external">MinimumOverDensityForRefinement</b> (external) - These float 
	  values (up to 5) are used if the CellFlaggingMethod is 2, 4, or 5 although in slightly
	  different ways.  For Method 5, this is the overdensity in terms of
	  (rho/&lt;rho> - 1), where rho is the density of the cell, and &lt;rho>
	  is the mean density.  For the others, the meaning is actually just
	  rho/&lt;rho> where rho is the density of the appropriate species. 
	  This value is converted into a mass, by multiplying by the volume of the
	  a top grid cell.  This result is then stored in the next parameter
	  (unless it is set directly in which case this parameter is ignored), and
	  this defines the mass resolution of the simulation.  Note that the
	  volume is of a top grid cell, so if you are doing a multi-grid initialization,
	  you must divide this number by r^(d*l) where r is the refinement factor,
	  d is the dimensionality and l is the (zero-based) lowest level.  For
	  example, for a two grid setup where a cell should be refined whenever the
	  mass exceeds 4 times the mean density of the subgrid, this value should
	  be 4 / (2^(3*1)) = 4 / 8 = 0.5.  Keep in mind that this parameter
	  has no effect if it is changed in a restart output; if you want to change
	  the refinement mid-run you will have to modify the next parameter. 
	  Up to five numbers may be specified here, each corresponding to the respective
	  CellFlaggingMethod. Default: 1.5</p></li>

      <li><p>
	  <b class="internal">MinimumMassForRefinement</b> (internal) - This float is usually set
	  by the parameter above and so is labeled internal, but it can be set by
	  hand.  It is the mass (in units such that the entire mass in the computational
	  volume is 1.0) above which a refinement occurs if the CellFlaggingMethod
	  is appropriately set. There are five numbers here again, as per the above
	  parameter.  Default: none</p></li>

      <li><p>
	  <b class="external">MinimumMassForRefinementLevelExponent</b> (external).  
	  This parameter
	  modifies the behaviour of the above parameter.  As it stands, the
	  refinement based on the MinimumMassForRefinement (hereafter Mmin) parameter
	  is complete Lagrangian.  However, this can be modified.  The
	  actual mass used is Mmin*r^(l*alpha) where r is the refinement factor,
	  l is the level and alpha is the value of this parameter 
	  (MinimumMassForRefinementLevelExponent). 
	  Therefore a negative value makes the refinement super-Lagrangian, while
	  positive values are sub-Lagrangian. There are up to five values specified
	  here, as per the above two parameters.  Default: 0.0</p></li>

      <li><p>
	  <b class="external">MinimumSlopeForRefinement</b> (external) - If 
	  CellFlaggingMethod is 1, then local gradients are used as the refinement 
	  criteria.  All
	  variables are examined and the relative slope is computed: abs(q(i+1)-q(i-1))/q(i). 
	  Where this value exceeds this parameter, the cell is marked for refinement. 
	  This causes problems if q(i) is near zero. This is a single integer (as
	  opposed to the list of five for the above parameters).  Default: 0.3</p></li>

      <li><p>
	  <b class="external">MinimumPressureJumpForRefinement</b> (external) - If 
	  refinement is done
	  by shocks, then this is the minimum (relative) pressure jump in one-dimension
	  to qualify for a shock.  The definition is rather standard (see Colella
	  and Woodward's PPM paper for example)  Default: 0.33</p></li>

      <li><p>
	  <b class="external">MinimumEnergyRatioForRefinement</b> (external) - For the 
	  dual energy formalism, and cell flagging by shock-detection, this is an extra filter
	  which removes weak shocks (or noise in the dual energy fields) from triggering
	  the shock detection.  Default: 0.1</p></li>

      <li><p>
	  <b class="external">FluxCorrection</b> (external) - This flag indicates if the 
	  flux fix-up
	  step should be carried out around the boundaries of the sub-grid to preserve
	  conservation (1 - on, 0 - off).  Strictly speaking this should always
	  be used, but I have found it to lead to a less accurate solution for cosmological
	  simulations because of the relatively sharp density gradients involved.
	  However, it does appear to be important when radiative cooling is turned
	  on and very dense structures are created (this note added sheepishly in
	  April/99). It does work with the ZEUS hydro method, but since velocity
	  is face-centered, momentum flux is not corrected.  Species quantities
	  are not flux corrected directly but are modified to keep the fraction constant
	  based on the density change.  Default: 1</p></li>

      <li><p>
	  <b class="external">InterpolationMethod</b> (external) - There should be a whole 
	  section
	  devoted to the interpolation method, which is used to generate new sub-grids
	  and to fill in the boundary zones of old sub-grids, but a brief summary
	  must suffice.  The possible values of this integer flag are shown
	  in the table below.  The names specify (in at least a rough sense)
	  the order of the leading error term for a spatial Taylor expansion, as
	  well as a letter for possible variants within that order.  The basic
	  problem is that you would like your interpolation method to be: multi-dimensional,
	  accurate, monotonic and conservative.  There doesn't appear to be
	  much literature on this, so I've had to experiment.  The first one
	  (ThirdOrderA) is time-consuming and probably not all that accurate. 
	  The second one (SecondOrderA) is the workhorse: it's only problem is that
	  it is not always symmetric.  The next one (SecondOrderB) is a failed
	  experiment, and SecondOrderC is not conservative.  FirstOrderA is
	  everything except for accurate.  If  HydroMethod = 2 (ZEUS),
	  this flag is ignored, and the code automatically uses SecondOrderC for
	  velocities and FirstOrderA for cell-centered quantities.  Default:
	  1</p>

	<center><table>
	      <tr>
		<td>0 - ThirdOrderA</td>
		<td>3 - SecondOrderC</td>
	      </tr>
	      <tr>
		<td>1 - SecondOrderA</td>
		<td>4 - FirstOrderA</td>
	      </tr>
	      <tr>
		<td>2 - SecondOrderB</td>
		<td> </td>
	      </tr>
	  </table></center></li>
	  <p></p>

      <li><p>
	  <b class="external">ConservativeInterpolation</b> (external)
	  - This flag (1 - on, 0 - off) indicates if the interpolation
	  should be done in the conserved quantities (e.g. momentum
	  rather than velocity).  Ideally, this should be done,
	  but it can cause problems when strong density gradients
	  occur.  This must(!) be set off for ZEUS
	  hydro (the code does it automatically). Default: 1</p></li>
      <li><p>
	  <b class="external">MinimumEfficiency</b> (external) - When
	  new grids are created during the rebuilding process, each
	  grid is split up by a recursive bisection process that
	  continues until a subgrid is either of a minimum size or has
	  an efficiency higher than this value.  The efficiency
	  is the ratio of flagged zones (those requiring refinement)
	  to the total number of zones in the grid.  This is a
	  number between 0 and 1 and should probably by around 0.4 for
	  standard three-dimensional runs.  Default: 0.2</p></li>

      <li><p>
	  <b class="external">NumberOfBufferZones</b> (external) -
	  Each flagged cell, during the regridding process, is
	  surrounded by a number of zones to prevent the phenomenon of
	  interest from leaving the refined region before the next
	  regrid.  This integer parameter controls the number
	  required, which should almost always be one.  Default:
	  1</p></li>

      <li><p>
	  <b class="external">RefineByJeansLengthSafetyFactor</b> (external) - If the 
	  Jeans length
	  refinement criterion (see CellFlaggingMethod) is being used, then this parameter
	  specifies the number of cells which must cover one Jeans length. Default: 4</p></li>

      <li><p>
	  <b class="external">StaticRefineRegionLevel[#]</b> (external) - This parameter 
	  is used to
	  specify regions of the problem that are to static refined, regardless of
	  other parameters.  This is mostly used as an internal mechanism to
	  keep the initial grid hierarchy in place, but can be specified by the user. 
	  Up to 20 static regions may be defined (this number set in macros_and_parameters.h),
	  and each static region is labeled starting from zero.  For each static
	  refined region, two pieces of information are required: (1) the region
	  (see the next two parameters), and (2) the level at which the refinement
	  is to occurs (0 implies a level 1 region will always exist). Default: none</p></li>

      <li><p>
	  <b class="external">StaticRefineRegionLeftEdge[#], 
	  StaticRefineRegionRightEdge[#]</b> (external)
	  - These two parameters specify the two corners of a statically refined
	  region (see the previous parameter). Default: none</p></li>
    </ul>

    <h3>
      <a NAME="Hydrodynamic Parameters"></a>Hydrodynamic Parameters</h3>

    <ul>
      <li><p>
	  <b class="external">HydroMethod</b> (external) - This integer specifies 
	  the hydrodynamics
	  method that will be used.  Currently implemented are: 0 - PPM DE (a
	  direct-Eulerian version of PPM), 1 - PPM LR (a Lagrange-Remap version of
	  PPM), 2 - ZEUS (a Cartesian, 3D version of Stone &amp; Norman).  The
	  PPM LR version is not recommended.  Note that if ZEUS is selected,
	  it automatically turns off ConservativeInterpolation and the DualEnergyFormalism
	  flags.  Default: 0</p></li>

      <li><p>
	  <b class="external">Gamma</b> (external) - The ratio of specific heats for 
	  an ideal gas
	  (used by all hydro methods).  If using multiple species (i.e. MultiSpecies
	  > 0), then this value is ignored in favour of a direct calculation (except
	  for PPM LR)  Default: 5/3.</p></li>

      <li><p>
	  <b class="external">CourantSafetyNumber</b> (external) - This is the maximum 
	  fraction of
	  the CFL-implied timestep that will be used to advance any grid.  A
	  value greater than 1 is unstable (for all explicit methods).  The
	  recommended value is 0.4.  Default: 0.6.</p></li>

      <li><p>
	  <b class="external">DualEnergyFormalism</b> (external) - The dual energy 
	  formalism is needed
	  to make total energy schemes such as PPM DE and PPM LR stable and accurate
	  in the "hyper-Machian" regime (i.e. where the ratio of thermal energy to
	  total energy &lt; ~0.001).  Turn on for cosmology runs with PPM DE
	  and PPM LR.  Automatically turned off when used with the hydro method
	  ZEUS.  Integer flag (0 - off, 1 - on).  When turned on, there
	  are two energy fields: total energy and thermal energy.  Default:
	  0</p></li>

      <li><p>
	  <b class="external">DualEnergyFormalismEta1, DualEnergyFormalismEta2</b> (external) - These
	  two parameters are part of the dual energy formalism and should probably
	  not be changed.  Defaults: 0.001 and 0.1 respectively.</p></li>

      <li><p>
	  <b class="external">PressureFree</b> (external) - A flag that is interpreted by the PPM
	  DE hydro method as an indicator that it should try and mimic a pressure-free
	  fluid.  A flag: 1 is on, 0 is off.  Default: 0</p></li>

      <li><p>
	  <b class="external">PPMFlatteningParameter </b>(external) - This is a PPM parameter to control
	  noise for slowly-moving shocks.  It is either on (1) or off (0). 
	  Default: 0</p></li>

      <li><p>
	  <b class="external">PPMDiffusionParameter </b>(external) - This is the 
	  PPM diffusion parameter
	  (see the Colella and Woodward method paper for more details).  It
	  is either on (1) or off (0).  Default: 1 
	  [Currently disabled (set to 0)]</p></li>

      <li><p>
	  <b class="external">PPMSteepeningParameter </b>(external) - A PPM modification designed
	  to sharpen contact discontinuities.  It is either on (1) or off (0). 
	  Default: 0</p></li>

      <li><p>
	  <b class="external">ZEUSQuadraticArtificialViscosity</b> (external) - This is the quadratic
	  artificial viscosity parameter C2 of Stone &amp; Norman, and corresponds
	  (roughly) to the number of zones over which a shock is spread.  Default:
	  2.0</p></li>

      <li><p>
	  <b class="external">ZEUSLinearArtificialViscosity</b> (external) - This is the linear artificial
	  viscosity parameter C1 of Stone &amp; Norman.  Default: 0.0</p></li>
    </ul>

    <h3>
      <a NAME="Cosmology Parameters"></a>Cosmology Parameters</h3>

    <ul>
      <li><p>
	  <b class="external">ComovingCoordinates</b> (external) - Flag (1 - on, 0 - off) that determines
	  if comoving coordinates are used or not.  In practice this turns on
	  or off the entire cosmology machinery.  Default: 0</p></li>

      <li><p>
	  <b class="external">CosmologyFinalRedshift</b> (external) - This parameter 
	  specifies the redshift when the calculation will halt.
	  Default: 0.0</p></li>

      <li><p>
	  <b class="external">CosmologyOmegaMatterNow</b> (external) - This is the contribution of
	  all non-relativistic matter (including HDM) to the energy density at the
	  current epoch (z=0), relative to the value required to marginally close
	  the universe. It includes dark and baryonic matter. Default: 1.0</p></li>

      <li><p>
	  <b class="external">CosmologyOmegaLambdaNow</b> (external) - This is the contribution of
	  the cosmological constant to the energy density at the current epoch, in
	  the same units as above. Default: 0.0</p></li>

      <li><p>
	  <b class="external">CosmologyComovingBoxSize</b> (external) - The size of the volume to
	  be simulated in Mpc/h (at z=0). Default: 64.0</p></li>

      <li><p>
	  <b class="external">CosmologyHubbleConstantNow</b> (external) - The Hubble constant at z=0,
	  in units of 100 km/s/Mpc. Default: 0.5</p></li>

      <li><p>
	  <b class="external">CosmologyInitialRedshift</b> (external) - The redshift for which the
	  initial conditions are to be generated. Default: 20.0</p></li>

      <li><p>
	  <b class="external">CosmologyMaxExpansionRate</b> (external) - This float controls the timestep
	  so that cosmological terms are accurate followed.  The timestep is
	  constrained so that the relative change in the expansion factor in a step
	  is less than this value.  Default: 0.01</p></li>

      <li><p>
	  <b class="external">CosmologyCurrentRedshift</b> (information only) - This is not strictly
	  speaking a parameter since it is never interpreted and is only meant to
	  provide information to the user.  Default: n/a</p></li>
    </ul>

    <h3>
      <a NAME="Gravity Parameters"></a>Gravity Parameters</h3>

    <ul>
      <li><p>
	  <b class="external">TopGridGravityBoundary </b>(external) - A single integer which specified
	  the type of  gravitational boundary conditions for the top grid. 
	  Possible values are 0 for periodic and 1 for isolated (for all dimensions). 
	  The isolated boundary conditions have not been tested recently, so caveat
	  emptor.  Default: 0</p></li>

      <li><p>
	  <b class="external">SelfGravity</b> (external) - This flag (1 - on, 0 - off) indicates if
	  the baryons and particles undergo self-gravity.</p></li>

      <li><p>
	  <b class="external">GravitationalConstant</b> (external) - This is the gravitational constant
	  to be used.  For cgs units it should be 4*pi*G.   For cosmology,
	  this value must be 1 for the standard units to hold.  Default: 4*pi.</p></li>

      <li><p>
	  <b class="external">GreensFunctionMaxNumber</b> (external) - The Green's functions for the
	  gravitational potential depend on the grid size, so they are calculated
	  on a as-needed basis.  Since they are often re-used, they can be cached. 
	  This integer indicates the number that can be stored.  They don't
	  take much memory (only the real part is stored), so a reasonable number
	  is 100. [Ignored in current version]. Default: 1</p></li>

      <li><p>
	  <b class="external">GreensFunctionMaxSize</b> - Reserved for future use.</p></li>

      <li><p>
	  <b class="external">S2ParticleSize</b> (external) - This is the gravitational softening
	  radius, in cell widths, in terms of the S2 particle described by Hockney
	  and Eastwood in their book Computer Simulation Using Particles.  A
	  reasonable value is 3.0. [Ignored in current version]. Default:
	  3.0</p></li>

      <li><p>
	  <b class="external">GravityResolution</b> (external) - This was a mis-guided attempt to
	  provide the capability to increase the resolution of the gravitational
	  mesh.  In theory it still works, but has not been recently tested. 
	  Besides, it's just not a good idea.  The value (a float) indicates
	  the ratio of the gravitational cell width to the baryon cell width. [Ignored
	  in current version].  Default: 1</p></li>

      <li><p>
	  <b class="external">ComputePotential</b> (external) - This flag 
	  (1 -on, 0 - off) indicates
	  if the gravitational potential is to be computed on the mesh.  This
	  is necessary if the energy conservation is to be computed.  [not tested]  
	  Default: 0</p></li>

      <li><p>
	  <b class="external">BaryonSelfGravityApproximation</b> (external) - This 
	  flag indicates if baryon
	  density is derived in a strange, expensive but self-consistent way (0 -
	  off), or by a completely reasonable and much faster approximation (1 -
	  on).  This is an experiment gone wrong; leave on. Well, actually,
	  it's important for very dense structures as when radiative cooling is turned
	  on, so set to 0 if using many levels and radiative cooling is on [ignored
	  in current version].  Default: 1</p></li>

      <li><p>
	  <b class="external">MaximumGravityRefinementLevel</b> (external) - This is the lowest (most
	  refined) depth that a gravitational acceleration field is computed. More
	  refined levels interpolate from this level, provided a mechanism for instituting
	  a minimum gravitational smoothing length. Default: MaximumRefinetLevel
	  (unless HydroMethod is ZEUS and radiative cooling is on, in which case
	  it is MaximumRefinementLevel - 3).</p></li>

      <li><p>
	  <b class="external">MaximumParticleRefinementLevel</b> (external) - This is the level at
	  which the dark matter particle contribution to the gravity is smoothed. 
	  This works in an inefficient way (it actually smoothes the particle density
	  onto the grid), and so is only intended for highly refined regions which
	  are nearly completely baryon dominated.  It is used to remove the
	  discreteness effects of the few remaining dark matter particles. 
	  Not used if set to a value less than 0.
          Default: -1</p></li>

      <li><p>
	  <b class="external">PointSourceGravity</b> (external) - This flag (1 - on, 0 - off) indicates
	  if there is to be a (constant) point source gravitational field. 
	  Default: 0</p></li>

      <li><p>
	  <b class="external">PointSourceGravityConstant</b> (external) - The magnitude of the point
	  source acceleration at a distance of 1 length unit.  Default: 1</p></li>

      <li><p>
	  <b class="external">PointSourceGravityPosition</b> (external) - If the PointSourceGravity
	  flag is turned on, this parameter specifies the center of the point-source
	  gravitational field.  Default: 0 0 0</p></li>

      <li><p>
	  <b class="external">UniformGravity</b> (external) - This flag (1 - on, 0 - off) indicates
	  if there is to be a uniform gravitational field.  Default: 0</p></li>

      <li><p>
	  <b class="external">UniformGravityDirection</b> (external) - This integer is the direction
	  of the uniform gravitational field: 0 - along the x axis, 1 - y axis, 2
	  - z axis.  Default: 0</p></li>

      <li><p>
	  <b class="external">UniformGravityConstant</b> (external) - Magnitude (and sign) of the
	  uniform gravitational acceleration.  Default: 1</p></li>
    </ul>

    <h3>
      <a NAME="Particle Parameters"></a>Particle Parameters</h3>

    <ul>
      <li><p>
	  <b class="external">ParticleBoundaryType</b> (external) - The boundary condition imposed
	  on particles.  At the moment, this parameter is largely ceremonial
	  as there is only one type implemented: periodic, indicated by a 0 value. 
	  Default: 0</p></li>

      <li><p>
	  <b class="external">ParticleCourantSafetyNumber</b> (external) - This somewhat strangely
	  named parameter is the maximum fraction of a cell width that a particle
	  is allowed to travel per timestep (i.e. it is a constant on the timestep
	  somewhat along the lines of it's hydrodynamic brother).  Default:
	  0.5</p></li>

      <li><p>
	  <b class="obsolete">NumberOfParticles </b>(obsolete) - Currently ignored by all initializers,
	  except for TestGravity and TestGravitySphere where it is the number of
	  test points.  Default: 0</p></li>

      <li><p>
	  <b class="internal">NumberOfParticleAttributes </b>(internal) - 
	  It is set to 3 if either StarParticleCreation or StarParticleFeedback is
	  set to 1 (TRUE).  Default: 0</p></li>

      <li><p>
	  <b class="external">ParallelParticleIO </b>(external) - Normally, for 
	  the mpi version, the particle data are read into the root processor and 
	  then distributed to separate processors. However, for very large number of
	  particles, the root processor may not have enough memory. If this toggle
	  switch is set on (i.e. to the value 1), then Ring i/o is turned on and each 
	  processor reads its own part of the particle data. More I/O is required,
	  but it is more balanced in terms of memory. ParallelRootGridIO and 
	  ParallelParticleIO MUST be set for runs involving > 64 cpus!
	  Default: 0 (FALSE).</p></li>

    </ul>

    <h3>
      <a NAME="Parameters for Additional Physics"></a>Parameters for Additional
      Physics</h3>

    <ul>
      <li><p>
	  <b class="external">RadiativeCooling</b> (external) - This flag (1 - on, 0 - off) controls
	  whether or not a radiative cooling module is called for each grid. 
	  There are currently two possibilities, controlled by the value of another
	  flag.  If the MultiSpecies flag is off, then equilibrium cooling is
	  assumed, and a file called <tt>cool_rates.in</tt> is read to set a cooling
	  curve.  This file consists of a set of temperature and the associated
	  cgs cooling rate; a sample compute with a metallicity Z=0.3 Raymond-Smith
	  code is provided in <tt>amr_mpi/exe/cool_rates.in</tt>.  If the Multispecies
	  flag is on, then the cooling rate is computed directly by the species abundances. 
	  This routine (which uses a backward differenced multi-step algorithm) was
	  plundered from the Hercules code written by Peter Anninos and Yu Zhang,
	  featuring rates from Tom Abel.  Default: 0</p></li>

      <li><p>
	  <b class="external">MultiSpecies</b> (external) - If this flag (1, 2, 3- on, 0 - off) is
	  on, then the code follows not just the total density, but also the ionization
	  states of Hydrogen and Helium.  If set to 2, then a nine-species model
	  (including H2, H2+ and H-) will be computed, otherwise only six species
	  are followed (H, H+, He, He+, He++, e-). If set to 3, then a 12 species
	  model is followed, including D, D+ and HD [Deuterium is currently broken]. 
	  This routine, like the last one, is based on work done by Abel, Zhang and
	  Anninos.  Default: 0</p></li>

      <li><p>
	  <b class="external">MultiMetals </b>(external) - This is a placeholder right now.  
	  It was added so that the user could turn on or off additional metal fields - 
	  currently there is the standard metallicity field (Metal_Density) and two additional 
	  metal fields (Z_Field1 and Z_Field2).  Acceptable values are 1 or 0, default 
	  0 (off). </p></li>

      <li><p>
	  <b class="external">StarParticleCreation</b> (external) - If set to 1 or 2, then one of
	  two possible, experimental, star formation algorithms is used.  The
	  algorithms are from 
          <a href="http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=1992ApJ...399L.113C&db_key=AST&high=3e9748c32a24652">Cen &amp; Ostriker (1992)</a> and the implementation is
	  by Chris Loken, Brian O'Shea and GLB.  The second algorithm (2) is
	  recommended.  Defaut: 0</p></li>

      <li><p>
	  <b class="external">StarParticleFeedback</b> (external) - If set to 1 or 2, then one of
	  two possible star feedback algorithms is used.  The second (StarParticleFeedback=2)
	  is recommended.  Default: 0</p></li>

      <li><p>
	  <b class="external">StarMakerOverDensityThreshold</b> (external) - The overdensity threshold
	  (relative to the total mean density, not just the dark matter mean density)
	  before star formation will be considered. Default: 100</p></li>

      <li><p>
	  <b class="external">StarMakerMassEfficiency</b> (external) - The fraction of identified
	  baryonic mass in a cell (Mass*dt/t_dyn) that is converted into a star
	  particle.  Default: 1</p></li>

      <li><p>
	  <b class="external">StarMakerMinimumMass</b> (external) - The 
	  minimum mass of star particle,
	  in solar masses.  Note however, the star maker algorithm 2 has a "stochastic"
	  star formation algorithm that will, in a pseudo-random fashion, allow star
	  formation even for very low star formation rates.  It attempts to do
	  so (relatively successfully according to tests) in a fashion that conserves
	  the global average star formation rate.  Default: 1e9</p></li>

      <li><p>
	  <b class="external">StarMakerMinimumDynamicalTime </b>(external) - When the star formation
	  rate is computed, the rate is proportional to M_baryon * dt/max(t_dyn,
	  t_max) where t_max is this parameter.  This effectively sets a limit
	  on the rate of star formation based on the idea that stars have a non-negligible
	  formation and life-time.  The unit is years.  Default: 1e6</p></li>

      <li><p>
	  <b class="external">StarMassEjectionFraction</b> (external) - The mass fraction of created
	  stars which is returned to the gas phase.  Default: 0.25</p></li>

      <li><p>
	  <b class="external">StarMetalYield</b> (external) - The mass fraction of metals produced
	  by each unit mass of stars created (i.e. it is multiplied by mstar, not
	  ejected).  Default: 0.02</p></li>

      <li><p>
	  <b class="external">StarEnergyToThermalFeedback</b> (external) - The fraction of the rest-mass
	  energy of the stars created which is returned to the gas phase as thermal
	  energy.  Default: 1e-5</p></li>

      <li><p>
	  <b class="external">StarEnergyToStellarUV</b> (external) - The fraction of the rest-mass
	  energy of the stars created which is returned as UV radiation with a young
	  star spectrum.  Default: 3e-6</p></li>

      <li><p>
	  <b class="external">StarEnergyToQuasarUV</b> (external) - The fraction of the rest-mass
	  energy of the stars created which is returned as UV radiation with a quasar
	  spectrum.  Default: 5e-6</p></li>

      <li><p>
	  <b class="external">RadiationFieldType</b> (external) - This integer parameter specifies
	  the type of radiation field that is to be used.  It can currently
	  only be used if MultiSpecies = 1 (i.e. no molecular H support).  The
	  following values are used: (1) - Haardt &amp; Madau spectrum with q_alpha=-1.5;
	  (2) - Haardt &amp; Madau spectrum with q_alpha = -1.8; (3) - reserved for
	  experimentation; (4) - H&amp;M spectrum (q_alpha=-1.5) supplemented with
	  an X-ray Compton heating background from Madau &amp; Efstathiou (see astro-ph/9902080); 
	  (9) - a constant molecular H2 photo-dissociation rate; (10) - internally
	  computed radiation field using the algorithm of Cen &amp; Ostriker; (11)
	  - same as previous, but with very, very simple optical shielding fudge.
	  Default: 0</p></li>

      <li><p>
	  <b class="external">RadiationFieldLevelRecompute</b> (external) - This integer parameter
	  is used only if the previous parameter is set to 10 or 11.  It controls
	  how often (i.e. the level at which) the internal radiation field is recomputed. 
	  Default: 0</p></li>

      <li><p>
	  <b class="external">RadiationSpectrumNormalization </b>(external) - This 
	  parameter was initially used to normalize the photo-ionization and 
	  photo-heating rates computed in the RadiationFieldCalculateRates() and 
	  then passed on to calc_photo_rates(), calc_rad() and calc_rates() routines. 
	  Later, the normalization as a separate input parameter was dropped for all 
	  cases by using the rates computed in RadiationFieldCalculateRates() with 
	  one exception: The molecular hydrogen (H2) dissociation rate. There a 
	  normalization is performed on the rate by multiplying it with 
	  RadiationSpectrumNormalization. Default: </p></li>

      <li><p>
	  <b class="external">UseMinimumPressureSupport</b> (external) - When radiative cooling is
	  turned on, and objects are allowed to collapse to very small sizes (i.e.
	  a few cells), and they are evolved for many, many dynamical times, then
	  unfortunate things happen. Primarily, there is some spurious angular momentum
	  generation, and possible some resulting momentum non-conservation. To alleviate
	  this problem, a very simple fudge was introduced: if this flag is turned
	  on, then a minimum temperature is applied to grids with level == MaximumRefinementLevel.
	  This minimum temperature is that required to make each cell Jeans stable
	  multiplied by the parameter below.  If you use this, it is advisable
	  to also set the gravitational smoothing length in the form of MaximumGravityRefineLevel
	  to 2 or 3 less than MaximumRefinementLevel.
	  Default: 0</p></li>

      <li><p>
	  <b class="external">MinimumPressureSupportParameter</b> (external) - This is the parameter
	  alluded to above. Very roughly speaking, is is the number of cells over
	  which a gravitationally bound small cold clump, on the most refined level,
	  will be spread over.
	  Default: 100</p></li>
    </ul>

    <h3>
      <a NAME="Test Problem Parameters"></a>Test Problem Parameters</h3>
    <ul>

    <h4>
      <a NAME="Shock Tube"></a>Shock Tube (1: <a href="ShockTube">unigrid</a> and 
      <a href="AMRShockTube">AMR</a>)</h4>
      <p>Riemann problem or arbitrary discontinuity breakup problem. The discontinuity initially 
      separates two arbitrary constant states: Left and Right. Default values correspond to the
      so called Sod Shock Tube setup (test 1.1). A table below contains a series of recommended 
      1D tests for hydrodynamic method, specifically designed to test the performance of the 
      Riemann solver, the treatment of shock waves, contact discontinuities, and rarefaction 
      waves in a variety of situations 
      (<a href="http://www.ing.unitn.it/~toroe/tito-book-rieman.html">Toro 1999</a>, p. 129).</p>

       <center><table>
	  <tr>
	    <td>Test</a></td>
	    <td>LeftDensity</td>
	    <td>LeftVelocity</td>
	    <td>LeftPressure</td>
	    <td>RightDensity</td>
	    <td>RightVelocity</td>
	    <td>RightPressure</td>
	  </tr>
	  <tr>
	    <td><a href="ShockTube1">1.1</a></td>
	    <td>1.0</td>
	    <td>0.0</td>
	    <td>1.0</td>
	    <td>0.125</td>
	    <td>0.0</td>
	    <td>0.1</td>
	  </tr>
	  <tr>
	    <td><a href="ShockTube2">1.2</a></td>
	    <td>1.0</td>
	    <td>-2.0</td>
	    <td>0.4</td>
	    <td>1.0</td>
	    <td>2.0</td>
	    <td>0.4</td>
	  </tr>
	  <tr>
	    <td><a href="ShockTube3">1.3</a></td>
	    <td>1.0</td>
	    <td>0.0</td>
	    <td>1000.0</td>
	    <td>1.0</td>
	    <td>0.0</td>
	    <td>0.01</td>
	  </tr>
	  <tr>
	    <td><a href="ShockTube4">1.4</a></td>
	    <td>1.0</td>
	    <td>0.0</td>
	    <td>0.01</td>
	    <td>1.0</td>
	    <td>0.0</td>
	    <td>100.0</td>
	  </tr>
	  <tr>
	    <td><a href="ShockTube5">1.5</a></td>
	    <td>5.99924</td>
	    <td>19.5975</td>
	    <td>460.894</td>
	    <td>5.99242</td>
	    <td>-6.19633</td>
	    <td>46.0950</td>
	  </tr>
	</table></center>
     <p></p>
     <ul>
      <li><p>
	  <b class="external">ShockTubeBoundary </b>(external) - Discontinuity position.  
          Default: 0.5</p></li>
      <li><p>
	  <b class="external">ShockTubeDirection </b>(external) - Discontinuity orientation.  
          Type: integer. Default: 0 (shock(s) will propagate in x-direction)</p></li>
      <li><p>
	  <b class="external">ShockTubeLeftDensity, ShockTubeRightDensity </b>(external) - The 
          initial gas density to the left and to the right of the discontinuity. Default: 1.0 
          and 0.125, respectively</p></li>
      <li><p>
	  <b class="external">ShockTubeLeftVelocity, ShockTubeRightVelocity </b>(external) - The
          same as above but for the velocity component in ShockTubeDirection. Default: 0.0, 0.0
          </p></li>
      <li><p>
	  <b class="external">ShockTubeLeftPressure, ShockTubeRightPressure </b>(external) - The
          same as above but for pressure.  Default: 1.0, 0.1</p></li>
      </ul>

    <h4>
      <a NAME="Wave Pool"></a>Wave Pool (<a href="WavePool">2</a>)</h4>
      <p>Wave Pool sets up a simulation with a 1D sinusoidal wave entering from the left boundary. 
      The initial active region is uniform and the wave is entered via inflow boundary conditions.</p>
      <ul>
      <li><p>
	  <b class="external">WavePoolAmplitude </b>(external) - The amplitude of the wave.  
          Default: 0.01 - a linear wave.</p></li>
      <li><p>
	  <b class="external">WavePoolAngle </b>(external) - Direction of wave propagation with 
          respect to x-axis.  Default: 0.0</p></li>
      <li><p>
	  <b class="external">WavePoolDensity </b>(external) - Uniform gas density in the pool.  
          Default: 1.0</p></li>
      <li><p>
	  <b class="external">WavePoolNumberOfWaves </b>(external) - The test initialization will work
          for one wave only. Default: 1</p></li>
      <li><p>
	  <b class="external">WavePoolPressure </b>(external) - Uniform gas pressure in the pool.  
          Default: 1.0</p></li>
      <li><p>
	  <b class="external">WavePoolSubgridLeft, WavePoolSubgridRight </b>(external) - Start and end
          positions of the subgrid.  Default: 0.0 and 0.0 (no subgrids)</p></li>
      <li><p>
	  <b class="external">WavePoolVelocity1(2,3) </b>(external) - x-,y-, and z-velocities.  
          Default: 0.0 (for all)</p></li>
      <li><p>
	  <b class="external">WavePoolWavelength </b>(external) - The wavelength.  
          Default: 0.1 (one-tenth of the box)</p></li>
      </ul>

    <h4>
      <a NAME="Shock Pool"></a>Shock Pool (3: <a href="ShockPool2D">unigrid 2D</a>, 
      <a href="AMRShockPool2D">AMR 2D</a> and 
      <a href="ShockPool3D">unigrid 3D</a>)</h4>
      <p>The Shock Pool test sets up a system which introduces a shock from the
      left boundary. The initial active region is uniform, and the shock wave 
      enters via inflow boundary conditions. 2D and 3D versions available.
      (D. Mihalas &amp; B.W. Mihalas, Foundations of 
      Radiation Hydrodynamics, 1984, p. 236, eq. 56-40.)</p>

      <ul>
      <li><p>
	  <b class="external">ShockPoolAngle </b>(external) - Direction of the shock 
          wave propagation with respect to x-axis. Default: 0.0</p></li>
      <li><p>
	  <b class="external">ShockPoolDensity </b>(external) - Uniform gas density 
          in the preshock region.  Default: 1.0</p></li>
      <li><p>
	  <b class="external">ShockPoolPressure </b>(external) -  Uniform gas pressure
          in the preshock region.  Default: 1.0</p></li>
      <li><p>
	  <b class="external">ShockPoolMachNumber </b>(external) - The ratio of the 
          shock velocity and the preshock sound speed. Default: 2.0</p></li>
      <li><p>
	  <b class="external">ShockPoolSubgridLeft, ShockPoolSubgridRight </b>
          (external) - Start and end positions of the subgrid. Default: 0.0 and 0.0 (no
          subgrids)</p></li>
      <li><p>
	  <b class="external">ShockPoolVelocity1(2,3) </b>(external) - Preshock gas 
          velocity (the Mach number definition above assumes a zero velocity in the
          laboratory reference frame.  
          Default: 0.0 (for all components)</p></li>
      </ul>

    <h4>
      <a NAME="Double Mach Reflection"></a>Double Mach Reflection (4)</h4>
      <p>A test for double Mach reflection of a strong shock (Woodward &amp; Colella 1984).
      Most of the parameters are "hardwired": d0 = 8.0, e0 = 291.25, 
      u0 = 8.25*sqrt(3.0)/2.0, v0 = -8.25*0.5, w0 = 0.0</p>
      <ul>
      <li><p>
	  <b class="external">DoubleMachSubgridLeft </b>(external) - Start position of the 
          subgrid.  Default: 0.0</p></li>
      <li><p>
	  <b class="external">DoubleMachSubgridRight </b>(external) - End positions of the 
          subgrid. Default: 0.0</p></li>
      </ul>

    <h4>
      <a NAME="Shock In A Box"></a>Shock in a Box (5)</h4>
      <p>A stationary shock front in a static 3D subgrid 
      (<a href="http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=1994ApJ...436...11A&db_key=AST&high=3e9748c32a03691">Anninos et al. 1994</a>). Initialization is done as in the <a href="#Shock Tube">Shock Tube</a> test.</p>
      <ul>
      <li><p>
	  <b class="external">ShockInABoxBoundary </b>(external) - Position of the shock.  
          Default: 0.5</p></li>
      <li><p>
	  <b class="external">ShockInABoxLeftDensity, ShockInABoxRightDensity </b>
          (external) - Densities to the Right and to the Left of the shock front.  
          Default: dL=1.0 and dR = dL*((Gamma+1)*m*m)/((Gamma-1)*m*m + 2), 
          where m=2.0.</p></li>
      <li><p>
	  <b class="external">ShockInABoxLeftVelocity, ShockInABoxRightVelocity </b>
          (external) - Velocities to the Right and to the Left of the shock front.  
          Default: vL=shockspeed and vR=shockspeed-m*sqrt(Gamma*pL/dL)*(1-dL/dR), 
          where m=2.0, shockspeed=0.9*sqrt(Gamma*pL/dL)*m.</p></li>
      <li><p>
	  <b class="external">ShockInABoxLeftPressure, ShockInABoxRightPressure </b>
          (external) - Pressures to the Right and to the Left of the shock front.  
          Default: pL=1.0 and pR=pL*(2.0*Gamma*m*m - (Gamma-1))/(Gamma+1), 
          where m=2.0.</p></li>
      <li><p>
	  <b class="external">ShockInABoxSubgridLeft, ShockInABoxSubgridRight </b>
          (external) -  Start and end
          positions of the subgrid.  Default: 0.0 (for both)</p></li>
      </ul>

    <h4>
      <a NAME="Zeldovich Pancake"></a>Zeldovich Pancake (<a href="ZeldovichPancake">20</a>)</h4>
      <p>A test for gas dynamics, expansion terms and self-gravity in both linear and 
      non-linear regimes 
      [<a href="http://zeus.ncsa.uiuc.edu:8080/gc3/P041/P041.html">Brian et al. (1995)</a>, 
      Sect. 3.4-3.5; <a href="http://arxiv.org/abs/astro-ph/9807121">Norman &amp; Brian (1998)</a>, 
      Sect. 4]</p>
      <ul>
      <li><p>
	  <b class="external">ZeldovichPancakeCentralOffset </b>(external) - Offset of the 
          pancake plane. Default: 0.0 (no offset)</p></li>
      <li><p>
	  <b class="external">ZeldovichPancakeCollapseRedshift </b>(external) - A free 
          parameter which determines the epoch of caustic formation. Default: 1.0</p></li>
      <li><p>
	  <b class="external">ZeldovichPancakeDirection </b>(external) - Orientation of the 
          pancake. Type: integer. Default: 0 (along the x-axis)</p></li>
      <li><p>
	  <b class="external">ZeldovichPancakeInitialTemperature </b>(external) - Initial 
          gas temperature. Units: degrees Kelvin. Default: 100</p></li>
      <li><p>
	  <b class="external">ZeldovichPancakeOmegaBaryonNow </b>(external) - Omega Baryon 
          at redshift z=0; standard setting. Default: 1.0</p></li>
      <li><p>
	  <b class="external">ZeldovichPancakeOmegaCDMNow </b>(external) - Omega CDM at 
          redshift z=0. Default: 0 (assumes no dark matter)</p></li>
      </ul>

    <h4>
      <a NAME="Pressureless Collapse">Pressureless Collapse</a> 
      (<a href="PressurelessCollapse">21</a>)</h4>
      <p>An 1D AMR test for the gravity solver and advection routines: the two-sided 
      one-dimensional collapse of a homogeneous plane parallel cloud in Cartesian coordinates.
      Isolated boundary conditions. Gravitational constant G=1; free fall time 0.399.
      The expansion terms are not used in this test.
      (<a href="http://zeus.ncsa.uiuc.edu:8080/gc3/P041/P041.html">Brian et al. 1995</a>, 
      Sect. 3.1).</p>
      <ul>
      <li><p>
	  <b class="external">PressurelessCollapseDirection </b>(external) - Coordinate direction. 
          Default: 0 (along the x-axis).</p></li>
      <li><p>
	  <b class="external">PressurelessCollapseInitialDensity </b>(external) - 
          Initial density (the fluid starts at rest).  
          Default: 1.0</p></li>
      <li><p>
	  <b class="external">PressurelessCollapseNumberOfCells </b>(external) - ???. 
          Default: GridDimension[PressurelessCollapseDirection] - 2</p></li>
      </ul>

    <h4>
      <a NAME="Adiabatic Expansion"></a>Adiabatic Expansion (<a href="AdiabaticExpansion">22</a>)</h4> 
      <p>A test for time-integration accuracy of the expansion terms (<a 
      href="http://zeus.ncsa.uiuc.edu:8080/gc3/P041/P041.html">Brian et al. 1995</a>, 
      Sect. 3.3).</p>
      <ul>
      <li><p>
	  <b class="external">AdiabaticExpansionInitialTemperature </b>(external) - Initial 
          temperature for Adiabatic Expansion test; test example assumes 1000 K. Default: 200. 
          Units: degrees Kelvin</p></li>
      <li><p>
	  <b class="external">AdiabaticExpansionInitialVelocity </b>(external) - Initial 
          expansion velocity.  Default: 100. Units: km/s</p></li>
      <li><p>
	  <b class="external">AdiabaticExpansionOmegaBaryonNow </b>(external) - Omega Baryon 
          at redshift z=0; standard value 1.0.  Default: 1.0</p></li>
      <li><p>
	  <b class="external">AdiabaticExpansionOmegaCDMNow </b>(external) - Omega CDM at 
          redshift z=0; default setting assumes no dark matter. Default: 0.0</p></li>
      </ul>

    <h4>
      <a NAME="Test Gravity"></a>Test Gravity (<a href="TestGravity">23</a>)</h4>
      <p>We set up a system in which there is one grid point with mass in order
      to see the resulting acceleration field.  If finer grids are specified,
      the mass is one grid point on the subgrid as well. Periodic boundary conditions
      are imposed (gravity).</p>
      <ul>
      <li><p>
	  <b class="external">TestGravityDensity </b>(external) - Density of the central peak.  
          Default: 1.0</p></li>
      <li><p>
	  <b class="external">TestGravityMotionParticleVelocity </b>(external) - 
          Initial velocity of test particle(s) in x-direction.  
          Default: 1.0</p></li>
      <li><p>
	  <b class="external">TestGravityNumberOfParticles </b>(external) - 
          The number of test particles of a unit mass.  
          Default: 0</p></li>
      <li><p>
	  <b class="external">TestGravitySubgridLeft, TestGravitySubgridRight </b>
          (external) - Start and end positions of the subgrid. Default: 0.0 and 0.0 (no
          subgrids)</p></li>
      <li><p>
	  <b class="external">TestGravityUseBaryons </b>(external) - Boolean switch.  
          Type: integer. Default: 0 (FALSE)</p></li>
      </ul>

      <h4>
      <a NAME="Spherical Infall"></a>Spherical Infall (<a href="SphericalInfall">24</a>)</h4>
      <p>A test based on <a href="http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=1985ApJS...58...39B&db_key=AST&high=3e9748c32a14398">Bertschinger's (1985)</a> 
       3D self-similar spherical infall solution onto an initially overdense 
       perturbation in an Einstein-de Sitter universe.</p>
      <ul>
      <li><p>
	  <b class="external">SphericalInfallCenter </b>(external) - 
          Coordinate(s) for the accretion center.  
          Default: top grid center</p></li>
      <li><p>
	  <b class="external">SphericalInfallFixedAcceleration </b>(external) - 
          Boolean flag. Type: integer.  
          Default: 0 (FALSE)</p></li>
      <li><p>
	  <b class="external">SphericalInfallFixedMass </b>(external) - ???.  
          Default: If SphericalInfallFixedMass is undefined and 
          SphericalInfallFixedAcceleration==TRUE, then 
          SphericalInfallFixedMass = SphericalInfallInitialPerturbation*TopGridVolume</p></li>
      <li><p>
	  <b class="external">SphericalInfallInitialPerturbation </b>(external) - 
          The perturbation of initial mass density.  
          Default: 0.1</p></li>
      <li><p>
	  <b class="external">SphericalInfallOmegaBaryonNow </b>(external) - 
          Omega Baryon at redshift z=0; standard setting.  
          Default: 1.0</p></li>
      <li><p>
	  <b class="external">SphericalInfallOmegaCDMNow </b>(external) - 
          Omega CDM at redshift z=0. Default: 0.0 (assumes no dark matter)  
          Default: 0.0</p></li>
      <li><p>
	  <b class="external">SphericalInfallSubgridIsStatic </b>(external) -  
          Boolean flag. Type: integer.  
          Default: 0 (FALSE)</p></li>
      <li><p>
	  <b class="external">SphericalInfallSubgridLeft, SphericalInfallSubgridRight </b>
          (external) - Start and end positions of the subgrid. Default: 0.0 and 0.0 (no
          subgrids)</p></li>
      <li><p>
	  <b class="external">SphericalInfallUseBaryons </b>(external) - 
          Boolean flag. Type: integer.  
          Default: 1 (TRUE)</p></li>
      </ul>

      <h4>
      <a NAME="Test Gravity Sphere"></a>Test Gravity: Sphere 
      (<a href="TestGravitySphere">25</a>)</h4>
      <p>Sets up a 3D spherical mass distribution and follows its evolution 
      to test the gravity solver.</p>
      <ul>
      <li><p>
	  <b class="external">TestGravitySphereCenter </b>(external) - 
	  The position of the sphere center.  
          Default: at the center of the domain</p></li>
      <li><p>
	  <b class="external">TestGravitySphereExteriorDensity </b>(external) - 
          The mass density outside the sphere.  
          Default: tiny_number</p></li>
      <li><p>
	  <b class="external">TestGravitySphereInteriorDensity </b>(external) - 
          The mass density at the sphere center.
          Default: 1.0</p></li>
      <li><p>
	  <b class="external">TestGravitySphereRadius </b>(external) - 
          Radius of self-gravitating sphere.  
          Default: 0.1</p></li>
      <li><p>
	  <b class="external">TestGravitySphereRefineAtStart </b>(external) - 
          Boolean flag. Type: integer.  
          Default: 0 (FALSE)</p></li>
      <li><p>
	  <b class="external">TestGravitySphereSubgridLeft, TestGravitySphereSubgridRight </b>
          (external) - Start and end positions of the subgrid. Default: 0.0 and 0.0 (no
          subgrids)</p></li>
      <li><p>
	  <b class="external">TestGravitySphereType </b>(external) - 
          Type of mass density distribution within the sphere. Options include: (0) uniform
          density distrubution within the sphere radius; (1) a power law with an index -2.0;
          (2) a power law with an index -2.25 (the exact power law form is, e.g., r^-2.25, 
          where r is measured in units of TestGravitySphereRadius).   
          Default: 0 (uniform density)</p></li>
      <li><p>
	  <b class="external">TestGravitySphereUseBaryons </b>(external) -
          Boolean flag. Type: integer .  
          Default: 1 (TRUE)</p></li>
      </ul>

      <h4>
      <a NAME="Gravity Equilibrium Test"></a>Gravity Equilibrium Test (26)</h4>
      <p>Sets up a hydrostatic exponential atmosphere with the pressure=1.0 and 
      density=1.0 at the bottom. 
      Assumes constant gravitational acceleration (uniform gravity field).</p>
      <ul>
      <li><p>
	  <b class="external">GravityEquilibriumTestScaleHeight </b>(external) - 
          The scale height for the exponential atmosphere .  
          Default: 0.1</p></li>
      </ul>

      <h4>
      <a NAME="Collapse test"></a>Collapse Test (<a href="CollapseTest">27</a>)</h4>
      <p>A self-gravity test.</p>
      <ul>
      <li><p>
	  <b class="external">CollapseTestInitialTemperature </b>(external) - Initial gas 
          temperature. Default: 1000 K. Units: degrees Kelvin</p></li>
      <li><p>
	  <b class="external">CollapseTestNumberOfSpheres </b>(external) - Number of spheres 
          to collapse; must be <= MAX_SPHERES=10 (see Grid.h for definition).  Default: 1</p></li>
      <li><p>
	  <b class="external">CollapseTestRefineAtStart </b>(external) - 
	  Boolean flag. Type: integer.
	  If TRUE, then initializing routine refines the grid to the 
	  desired level. Default: 1 (TRUE)</p></li>
      <li><p>
	  <b class="external">CollapseTestSphereCoreRadius </b>(external) - An array of core radii 
          for collapsing spheres.  Default: 0.1 (for all spheres)</p></li>
      <li><p>
	  <b class="external">CollapseTestSphereDensity </b>(external) - An array of density values 
          for collapsing spheres.  Default: 1.0 (for all spheres)</p></li>
      <li><p>
	  <b class="external">CollapseTestSpherePosition </b>(external) - A two-dimensional array 
          of coordinates for sphere centers. Type: float[MAX_SPHERES][MAX_DIMENSION]. Default for 
          all spheres: 0.5*(DomainLeftEdge[dim] + DomainRightEdge[dim])</p></li>
      <li><p>
	  <b class="external">CollapseTestSphereRadius </b>(external) -  An array of radii for 
          collapsing spheres.  Default: 1.0 (for all spheres)</p></li>
      <li><p>
	  <b class="external">CollapseTestSphereTemperature </b>(external) - An array of 
          temperatures for collapsing spheres.  Default: 1.0. Units: degrees Kelvin</p></li>
      <li><p>
	  <b class="external">CollapseTestSphereType </b>(external) - An integer array of sphere 
          types. Default: 0</p></li>
      <li><p>
	  <b class="external">CollapseTestSphereVelocity </b>(external) - A two-dimensional array of 
          sphere velocities. Type: float[MAX_SPHERES][MAX_DIMENSION]. Default: 0.0</p></li>
      <li><p>
	  <b class="external">CollapseTestUniformVelocity </b>(external) - Uniform velocity. 
          Type: float[MAX_DIMENSION]. Default: 0 (for all dimensions)</p></li>
      <li><p>
	  <b class="external">CollapseTestUseColour </b>(external) - Boolean flag.  
           Type: integer. Default: 0 (FALSE)</p></li>
      <li><p>
	  <b class="external">CollapseTestUseParticles </b>(external) - Boolean flag.  
           Type: integer. Default: 0 (FALSE)</p></li>
      </ul>

      <h4>
      <a NAME="Cosmology Simulation"></a>Cosmology Simulation (<a href="AMRCosmologySimulation">30</a>)</h4>
      <p>A sample cosmology simulation.</p>
      <ul>

      <li><p>
	  <b class="external">CosmologySimulationDensityName </b>
	  (external) - This is the name of the file which
          contains initial data for baryon density. Type: string. 
	  Example: GridDensity.
          Default: none</p></li>

      <li><p>
	  <b class="external">CosmologySimulationTotalEnergyName </b>
	  (external) - This is the name of the file which
          contains initial data for total energy. 
          Default: none</p></li>

      <li><p>
	  <b class="external">CosmologySimulationGasEnergyName </b>
	  (external) - This is the name of the file which
          contains initial data for gas energy. 
          Default: none</p></li>

      <li><p>
	  <b class="external">CosmologySimulationVelocity[123]Name </b>
	  (external) - These are the names of the files which
          contain initial data for gas velocities. Velocity1 - x-component;
	  Velocity2 - y-component; Velocity3 - z-component. 
          Default: none</p></li>

      <li><p>
	  <b class="external">CosmologySimulationParticleMassName </b>
	  (external) - This is the name of the file which
          contains initial data for particle masses. 
          Default: none</p></li>

      <li><p>
	  <b class="external">CosmologySimulationParticlePositionName </b>
	  (external) - This is the name of the file which
          contains initial data for particle positions. 
          Default: none</p></li>

      <li><p>
	  <b class="external">CosmologySimulationParticleVelocityName </b>
	  (external) - This is the name of the file which
          contains initial data for particle velocities. 
          Default: none</p></li>

      <li><p>
	  <b class="external">CosmologySimulationNumberOfInitialGrids </b>
	  (external) - The number of grids at startup. 1 means top grid only.
	   If >1, then nested grids are to be defined by the following parameters.
          Default: 1</p></li>

      <li><p>
	  <b class="external">CosmologySimulationSubgridsAreStatic </b>
	  (external) - Boolean flag, defines whether the subgrids introduced
          at the startup are static or not. Type: integer.
          Default: 1 (TRUE) </p></li>

      <li><p>
	  <b class="external">CosmologySimulationGridLevel </b>
	  (external) - An array of integers setting the level(s)
	  of nested subgrids. Max dimension MAX_INITIAL_GRIDS is defined in 
	  CosmologySimulationInitialize.C as 10.
          Default for all subgrids: 1, 0 - for the top grid (grid #0)</p></li>

      <li><p>
	  <b class="external">CosmologySimulationGridDimension[#] </b>
	  (external) - An array (arrays) of 3 integers setting the dimensions
	  of nested grids. Index starts from 1.
	  Max number of subgrids MAX_INITIAL_GRIDS is defined in 
	  CosmologySimulationInitialize.C as 10.
          Default: none</p></li>

      <li><p>
	  <b class="external">CosmologySimulationGridLeftEdge[#] </b>
	  (external) - An array (arrays) of 3 floats setting the left edge(s)
	  of nested subgrids. Index starts from  1.
	  Max number of subgrids MAX_INITIAL_GRIDS is defined in 
	  CosmologySimulationInitialize.C as 10.
          Default: none</p></li>

      <li><p>
	  <b class="external">CosmologySimulationGridRightEdge[#] </b>
	  (external) - An array (arrays) of 3 floats setting the right edge(s)
	  of nested subgrids. Index starts from  1.
	  Max number of subgrids MAX_INITIAL_GRIDS is defined in 
	  CosmologySimulationInitialize.C as 10.
          Default: none</p></li>

      <li><p>
	  <b class="external">CosmologySimulationUseMetallicityField </b>
	  (external) - Boolean flag. Type: integer.
          Default: 0 (FALSE)</p></li>

      <li><p>
	  <b class="external">CosmologySimulationInitialFractionH2I </b>
	  (external) - The fraction of molecular 
	  hydrogen (H_2) at InitialRedshift.
	  This and the following chemistry parameters are used if MultiSpecies
	  is defined as 1 (TRUE).
          Default: 2.0e-20</p></li>

      <li><p>
	  <b class="external">CosmologySimulationInitialFractionH2II </b>
	  (external) - The fraction of singly ionized molecular 
	  hydrogen (H2+) at InitialRedshift.
          Default: 3.0e-14</p></li>

      <li><p>
	  <b class="external">CosmologySimulationInitialFractionHeII </b>
	  (external) - The fraction of singly ionized helium at InitialRedshift.
          Default: 1.0e-14</p></li>

      <li><p>
	  <b class="external">CosmologySimulationInitialFractionHeIII </b>
	  (external) - The fraction of doubly ionized helium at InitialRedshift.
          Default: 1.0e-17</p></li>

      <li><p>
	  <b class="external">CosmologySimulationInitialFractionHII </b>
	  (external) - The fraction of ionized hydrogen at InitialRedshift.
          Default: 1.2e-5</p></li>

      <li><p>
	  <b class="external">CosmologySimulationInitialFractionHM </b>
	  (external) - The fraction of negatively charged hydrogen (H-) at InitialRedshift.
          Default: 2.0e-9</p></li>

      <li><p>
	  <b class="external">CosmologySimulationInitialTemperature </b>
	  (external) - A uniform temperature value at InitialRedshift (needed
	  if the initial gas energy field is not supplied).
          Default: 550*((1.0 + InitialRedshift)/201)^2</p></li>

      <li><p>
	  <b class="external">CosmologySimulationOmegaBaryonNow </b>
	  (external) -  This is the contribution of baryonic matter to the energy
	  density at the current epoch (z=0), relative to the value 
	  required to marginally close the universe. Typical value 0.06.
          Default: 1.0</p></li>

      <li><p>
	  <b class="external">CosmologySimulationOmegaCDMNow </b>
	  (external) - This is the contribution of CDM to the energy
	  density at the current epoch (z=0), relative to the value 
	  required to marginally close the universe. Typical value 0.94.
          Default: 0.0 (no dark matter)</p></li>
      </ul>

      <h4>
      <a NAME="Supernova Restart Simulation"></a>Supernova Restart Simulation 
      (40)</h4>
      <p>All of the supernova parameters are to be put into a restart dump's 
      parameter file.  Note that ProblemType must be reset to 40, otherwise 
      these are ignored.</p>
      <ul>

      <li><p>
	  <b class="external">SupernovaRestartEjectaCenter[#] </b>(external) - Input 
	  is a trio of coordinates in code units where the supernova's 
	  energy and mass ejecta will be centered.  Default: FLOAT_UNDEFINED
	  </p></li>

      <li><p>
	  <b class="external">SupernovaRestartEjectaEnergy </b>(external) - The 
	  amount of energy instantaneously output in the simulated supernova, 
	  in units of 1e51 ergs.  Default:  1.0</p></li>

      <li><p>
	  <b class="external">SupernovaRestartEjectaMass </b>(external) - The 
	  mass of ejecta in the supernova, in units of solar masses.  
	  Default:  1.0</p></li>

      <li><p>
	  <b class="external">SupernovaRestartEjectaRadius </b>(external) - The 
	  radius over which the above two parameters are spread.  This is 
	  important because if it's too small the timesteps basically go to zero 
	  and the simulation takes forever, but if it's too big then you loose 
	  information.  Units are parsecs.  Default: 1.0 pc</p></li>

      <li><p>
	  <b class="external">SupernovaRestartName </b>(external) - This is 
	  the name of the restart data dump that the supernova problem is 
	  initializing from.</p></li>

      <li><p>
	  <b class="reserved">SupernovaRestartColourField </b> - Reserved 
	  for future use.</p></li>

      </ul>
    </ul>

    </ul>

    <h3>
      <a NAME="Other external Parameters"></a>Other External Parameters</h3>

    <ul>
      <li><p>
	  <b class="external">huge_number </b>(external) - The largest 
	  reasonable number.  Rarely used.  Default: 1e+20</p></li>

      <li><p>
	  <b class="external">tiny_number</b> (external) - A number 
	  which is smaller than all physically reasonable numbers. 
	  Used to prevent divergences and divide-by-zero in the following C++ functions: 
	  ComputeElementalDensity(),
	  ComputePressure(), ComputePressureDualEnergyFormalism(), ComputeTemperatureField(),
	  ComputeTimeStep(), CorrectForRefinedFluxes(). Problem dependent. 
	  Modify with caution! Default: 1e-20. 
	  <p>A currently independent analog, 
	  <b>tiny</b>, defined in fortran.def, does the same job for a large family of 
	  FORTRAN routines:
	  calcdiss(), calc_dt(), calc_rates(), colh2diss(), coll_rates(), cool1d_multi(),
	  cool1d(), cool_multi_time(), cool_time(), euler(), grid_cic(), interp3d(), inteuler(),
	  int_lin3d(), intrmp(), lgrg(), multi_cool(), ppm_de(), ppm_lr(), solve_cool(),
	  solve_rate(), tscint[123]d(), zeus_main(), zeus_source(). Modification of <b>tiny</b>
	  must be done with caution and currently requires recompiling the code, since 
	  <b>tiny</b> is not a parameter yet.</p></p></li>

      <li><p>
	  <b class="reserved">TimeActionParameter[#] </b> - Reserved 
	  for future use.</p></li>

      <li><p>
	  <b class="reserved">TimeActionRedshift[#] </b> - Reserved 
	  for future use.</p></li>

      <li><p>
	  <b class="reserved">TimeActionTime[#] </b> - Reserved for 
	  future use.</p></li>

      <li><p>
	  <b class="reserved">TimeActionType[#] </b> - Reserved for 
	  future use.</p></li>
    </ul>

    <h3>
      <a NAME="Other Internal Parameters"></a>Other Internal Parameters</h3>

    <ul>
      <li><p>
	  <b class="reserved">TimeLastRestartDump</b> - Reserved for 
	  future use.</p></li>

      <li><p>
	  <b class="internal">TimeLastDataDump</b> (internal) - 
          The code time at which the last time-based
	  output occurred.</p></li>

      <li><p>
	  <b class="reserved">TimeLastHistoryDump</b> - Reserved for 
	  future use.</p></li>

      <li><p>
	  <b class="internal">TimeLastMovieDump</b> (internal) - 
	  The code time at which the last movie
	  dump occurred.</p></li>

      <li><p>
	  <b class="reserved">CycleLastRestartDump</b> - Reserved for 
	  future use.</p></li>

      <li><p>
	  <b class="internal">CycleLastDataDump</b> (internal) - The 
	  cycle number at which the last
	  cycle-based output occurred.</p></li>

      <li><p>
	  <b class="reserved">CycleLastHistoryDump</b> - Reserved for 
	  future use.</p></li>

      <li><p>
	  <b class="reserved">InitialCPUTime</b> - Reserved for 
	  future use.</p></li>

      <li><p>
	  <b class="internal">InitialCycleNumber</b> (internal) - 
	  One cycle is one top grid timestep. 
	  This is the cycle number of the current step. Default: 0</p></li>

      <li><p>
	  <b class="reserved">RestartDumpNumber</b> - Reserved for 
	  future use.</p></li>

      <li><p>
	  <b class="internal">DataLabel[#] </b>(internal) - These are printed 
	  out into the restart dump parameter file. One Label is produced per 
	  baryon field with the name of that baryon field. The same labels are
	  used to name data sets in HDF files.</p></li>

      <li><p>
	  <b class="reserved">DataUnits[#] </b> - Reserved for 
	  future use.</p></li>

      <li><p>
	  <b class="internal">DataDumpNumber</b> (internal) - The 
	  identification number of the next
	  output file (the 0000 part of the output name).  This is used and
	  incremented by both the cycle based and time based outputs.  
	  Default: 0</p></li>

      <li><p>
	  <b class="reserved">HistoryDumpNumber</b> - Reserved for 
	  future use.</p></li>

      <li><p>
	  <b class="internal">MovieDumpNumber</b> (internal) - The 
	  identification number of the next
	  movie output file.  Default: 0</p></li>

      <li><p>
	  <b class="internal">VersionNumber </b>(internal) - Sets 
	  the version number of the code which is written out to restart 
	  dumps.</p></li>
    </ul>

    <h3>
      <a NAME="Parameters to be Described"></a>Parameters to be Described</h3>

    <ul>
      <li><p>
	  <b class="external">PointSourceGravityCoreRadius </b>(external)</p></li>
    </ul>

    <hr WIDTH="100%">last modified: June 27, 2003
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